Technical Field
The present invention relates to a welded portion inspection method for inspecting a welded portion, and particularly to an inspection method for inspecting a welded state of a welded portion formed when a plurality of workpieces are welded together using laser light.
Background Art
Conventionally, when two steel plates are overlapped and laser-welded, for example, a welded portion formed by the laser welding is subjected to quality evaluation. As an example of a method for evaluating the quality of the welded portion formed by laser welding (welded portion inspection method), Patent Document 1 discloses a method of inspecting the welded portion using reflected light of laser light.
In this example, a laser torch irradiates the workpieces with a YAG laser, for example, and laser reflected light is received by a first light-receiving/output means from diagonally above and forwardly of the direction in which the welding proceeds. A second light-receiving/output means receives welding light including vapor light emission (plume) or laser reflected light in a coaxial direction with respect to the direction of laser light irradiation. The laser reflected light and the welding light simultaneously received from the predetermined two directions are converted into electric signals corresponding to respective intensities, and the weld quality is determined based on the intensity of the electric signals or its change.